1.What are the core characteristics and applicable scenarios of ordinary carbon steel pipes?
Core Characteristics: Low carbon content (≤0.25%), medium strength (tensile strength 315-510 MPa), excellent plasticity (elongation ≥21%), easy to bend and weld, and prone to surface rust (no corrosion resistance).
Typical Applications:
Low-load structural parts: such as furniture brackets, clothes drying rack tubes, and simple mechanical frames (not subject to high pressure/stress);
Low-pressure fluid transport: such as household tap water pipes (short-term use, requiring simple anti-corrosion treatment such as painting), and general mechanical lubricating oil lines (no corrosive media);
Low-cost machined parts: such as toy accessories and small agricultural tool parts (requires precision but low strength and lifespan).
2.What are the core characteristics and applicable scenarios of high-quality carbon steel?
Core Characteristics: Controllable carbon content (10#: 0.07%-0.14%, 20#: 0.17%-0.24%, 45#: 0.42%-0.50%), high purity (low impurities), and more stable performance. Low-carbon steel (10#, 20#) offers excellent plasticity and ease of welding; medium-carbon steel (35#, 45#) offers higher strength (45# tensile strength ≥600 MPa), and can be further enhanced through quenching and tempering (quenching and tempering).
Typical Applications:
Low-carbon steel (10#, 20#): Emphasizes "fluid transport + easy processing," such as low-pressure oil pipes in hydraulic systems, automotive cooling water pipes, and instrument piping (requiring bending and forming, and non-corrosive media); sleeves and bushings in mechanical structures (requiring coordination with other components, requiring high precision but low loads). Medium carbon steel (35#, 45#): focuses on "medium strength + wear resistance", such as mechanical shaft parts (tempered after cold rolling to improve hardness and toughness), gear blanks, and cylinder piston rods (need to withstand certain impact and friction).
3.What are the core properties and typical applications of low alloy high strength steel?
Core Characteristics: Mn addition (1.2%-1.6%), tensile strength ≥470 MPa (significantly higher than Q235's 375 MPa), excellent low-temperature toughness (maintains good ductility at -40°C), excellent weldability, and high cost-effectiveness.
Typical Applications:
Engineering structural parts: such as large machinery supports, tower crane booms, and steel factory building columns (requiring lightweight and high strength to reduce deadweight);
Medium- and high-pressure fluid transportation: such as low-pressure oil and natural gas pipelines (for field environments requiring resistance to low temperatures and certain pressures), and main hydraulic system pipes (for construction machinery such as excavators and loaders).
4.What are the core properties and typical applications of alloy structural steel?
Core Properties: The addition of Cr (increases hardness and wear resistance) and Mo (increases heat resistance and fatigue resistance) allows for significant performance optimization through heat treatment (carburizing, quenching and tempering).
20Cr: Low carbon, resulting in high surface hardness (HRC 58-62) and excellent core toughness after carburizing;
40Cr: Medium carbon, resulting in high strength (tensile strength ≥980 MPa) and balanced toughness after quenching and tempering;
42CrMo: Contains Mo, offering optimal heat resistance and fatigue resistance, suitable for high temperatures and high loads.
Typical Applications:
20Cr: Automotive transmission gears and bearing rings (requires surface wear resistance and core impact resistance);
40Cr: Mechanical spindles, lead screws, and high-pressure cylinder barrels (requires high torque and high pressure resistance while maintaining toughness);
20CrMo/42CrMo: High-end equipment components, such as aerospace piping (high-temperature resistance), generator rotor shafts (fatigue resistance), and oil drill pipe (for deep-well high-temperature and high-pressure environments).
5.What are the core properties and typical applications of heat-resistant steel?
Core Properties: Added Cr (1.0%-1.5%) and Mo (0.4%-0.6%), resulting in high-temperature strength (maintaining stable mechanical properties at 500°C) and excellent oxidation resistance (not susceptible to oxidation or peeling at high temperatures).
Typical Applications: Heat exchangers, boiler superheater tubes, and turbine air ducts (used in the power and chemical industries, requiring long-term operation in temperatures between 300°C and 500°C).